Washington — The United Auto Workers added nearly 15,000 new members in 2017, a 3.6 percent increase, according to documents filed Thursday with the U.S. Department of Labor.

The union said in the filing that it had 430,871 members last year, up from the 415,963 it had in 2016. It marks the eighth straight year the union has grown its ranks after reaching a low of 355,191 in 2009.

The UAW attributed the growth in its membership to successful organizing drives in the gaming, higher education, heavy truck and automotive suppliers sectors. The union said there was also modest growth in auto assembly. Outgoing UAW President Dennis Williams said in a statement the 2017 membership figures shows “the state of the UAW is strong.”

The union is coming off of a trying year in which it was embroiled by scandal involving allegations of a multi-million-dollar conspiracy to divert worker training funds within the top ranks of Fiat Chrysler Automobiles NV and the union that led to the indictments of five people.

Additionally, the UAW faltered it its effort to gain a foothold in a non-union auto plant that is located in a predominantly “right-to-work” states in the South when Nissan workers at the Japanese manufacturer’s Canton Assembly Plant in Mississippi voted nearly 2-to-1 against joining the labor union. The defeat marked the third time in nearly 30 years that Nissan workers in the South have voted against joining the UAW. Workers at Nissan’s Smyrna, Tennessee, plant voted against joining the UAW by 2-to-1 margins in 1989 and 2001.

The UAW has had trouble making gains beyond its Midwest base of factories owned by Detroit’s Big Three where the union has been established for decades.

The UAW’s filing did not break out membership for Michigan, where a right-to-work law took effect in March 2013. However, there was a increase in overall union membership in the state by about 1.2 percent in 2017, according to statistics released in January by the federal government.

The Michigan right-to-work law prohibits union contracts from requiring “fair share” fees as a condition of employment to pay for the cost of collective bargaining agreements.

The law was challenged in court, but the Michigan Supreme Court ruled in July 2015 that about 35,000 state employees should have never been subject to paying union fees, giving conservative supporters of the state’s right-to-work law a major victory.

The U.S. Department of Labor’s Bureau of Labor Statistics said in January the number of union members in Michigan increased from 606,000 in 2016 to 658,000 last year, going from 14.4 to 15.6 percent of the workforce.

The Department of Labor filing showed the UAW spent $7,073,237 on political activities and lobbying in 2017, and $673,121 on contributions, gifts and grants. It says the union has $947,204,270 in net assets.

The UAW’s membership last topped 500,000 in 2006, when it reported having 538,448 members. The union had more than 701,000 members in 2002.